MANDKLIC ACID 205 is poured out into a mortar which is placed in the fume cup- board, the window ot which is drawn down so as to protect the face, rive grams of sodium are introduced in small pieces, the size of a pea, and pressed with a pestle under the surface of the mercury. Kach piece dissolves with a bright flash. The amalgam is poured out whilst semi-fluid on to an iron tray, broken up, and kept in a wide-necked stoppered bottle.1 The cinnamic acid and water are introduced into a strong beaker or bottle (300 c.c.), and the liquid made slightly alkaline with caustic soda, which dissolves the acid forming the sodium salt. The sodium amalgam is added in small pieces from time to time and the liquid thoroughly agitated. The solution, which remains clear, becomes slightly warm, and the amalgam soon liquefies, but no hydrogen is evolved until towards the end of the operation. When the whole of the amalgam has been added, and bubbles of gas cease to be given off, the solution is decanted from the mercury, which is rinsed with water. On acidifying the solution with hydrochloric acid, hydrocinnamic acid is precipitated as a colourless oil, which solidifies on stand- ing. It maybe recrystalliscd from a large quantity of warm water. Yield, 8—-9 grams. 7V^/vr//V.v.—• Long colourless needles; m. p. 47° ; b. p. 280°; soluble in water and alcohol ; volatile in steam. See Appendix^ p. 306. l^W- PRKP A RATION 96, jfl Mandelic Acid, C0Mfl.CH(OH).COOH || iifjfe:'.! Friedliinder, Thccrfarbcnfabrikation IV, 160. fit ;- 15 grins, benxaklehyde. |- \ 50 c.c. cone, sodium bisulphite solution. if \ 12 grms. potassium cyanide (in 20 c.c. water). if p The benxaklehyde and sodium bisulphite are mixed together I j and stirred. The mixture forms a semi-solid mass of the 1 \ 1 If larger quantities uf amalgam are required, the mercury is heated in a small if f enamelled pan, or crucible, the sodium added, in one lot, and the vessel immediately closed with a ltd, which is held down with long crucible tongs until the reaction is over, and then poured out whilst fluid.